Inserter for minimally invasive joint surgery

ABSTRACT

An acetabular impactor aids a surgeon in controlling the installation of an acetabular cup prosthesis having a central, female aperture. The impactor includes an impactor head, housing and a locking mechanism. The housing is attached to the impactor head, the housing enclosing a drive train having, at a far end, a prosthesis engaging thread, and at the opposite end, a handle which facilitates turning of the drive train by the operator. The locking mechanism is associated with the housing which selectively locks the drive train, and thus the prosthesis, in position. The opposite end of the drive train has a latch device which enables quick removal from the housing for cleaning and sterilization.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims US priority to U.S. Ser. Nos. 60/518,768; 60/548,542; and 60/561,141, filed Nov. 10, 2003, Feb. 26, 2004, and Apr. 10, 2004, respectively, and, under the Paris Convention to PCT application PCT/IB2004/003676 filed 10 Nov. 2004 and U.S. Ser. No. 60/634,467 filed Dec. 9, 2004.

BACKGROUND OF THE INVENTION

This invention relates to surgical inserters for aiding in installing orthopedic prostheses, and, more particularly, to easily sterilizable inserters for installing acetabular implants in the acetabular socket.

Complicated mechanical devices have crevices and recesses that are difficult, if not almost impossible to clean with ease. Devices that are not properly cleaned and sterilized run the risk of disease transfer from patient to patient following the emergence of certain “prions” that are not killed by normal hospital sterilisation and need to be physically removed by washing/rinsing.

Further, in surgical procedures in which access to the treatment site is limited, it is difficult to use current solutions without subjecting the patient to repeated abrasion and tissue trauma when inserting and extracting surgical instruments.

Further, the insertion of the implant is often problematic, and the orientation of the implant, particularly any fixing holes that might be pre-drilled in the implant is often critical to minimize recovery time of the patient. Still further, once the appropriate position of the implant is selected, it is often difficult to ensure that the position does not change upon insertion of the assembly through the incision.

What is needed therefore is an inserter that is easily adjustable, disassemblable, and cleanable. Further, what is needed is an inserter that enables the surgeon to better maneuver position and install an implant in a particular angular orientation.

SUMMARY OF THE INVENTION

An acetabular inserter aids a surgeon in controlling the installation of an acetabular cup prosthesis generally having a central, female aperture. The inserter has a housing which encloses a drive train having, at a far end, a prosthesis engaging interface, and at the opposite end, a handle which facilitates turning of the drive train by the operator. The inserter enables easy orientation of a prosthesis attached to its end, which is important because the prosthesis often has pre-drilled holes and thus, these must be properly positioned prior to fastening through these holes.

An objective of the invention is to be “easily cleaned” by quick and modular disassembly which enables access to all surfaces that they can be cleaned, the reduction in number of small radius internal corners, crevices and small gaps and the absence of blind holes.

Another object of the invention is to provide an inserter which enables the implant to be locked in an angular orientation prior to installation of the implant.

Another object of the invention is to provide a dual mechanism that uses common components to lock the implant in place as well as to provide for easy disassembly for cleaning and sterilization.

Another object of the invention is to minimise the number of pieces and the risk that parts could be lost.

BRIEF DESCRIPTION OF THE DRAWINGS

The attached drawings represent, by way of example, different embodiments of the subject of the invention.

FIG. 1A is a cross-sectional side view of the inserter of the invention.

FIG. 1B is a side view of the inserter of the invention.

FIG. 1C is a perspective view of the inserter of the invention showing a one way catch mechanism.

FIG. 2A is an operational side view of the inserter of the invention.

FIG. 2B is an operational back view of the inserter of the invention.

FIG. 3A is a perspective view of the inserter of the invention, showing a step of disassembly for cleaning.

FIG. 3B is a perspective view of the inserter of the invention, showing another step of disassembly for cleaning.

FIG. 3C is a perspective view of the inserter of the invention, showing a stage of disassembly for cleaning.

FIG. 3D is a perspective view of the inserter of the invention, showing a stage of re-assembly after cleaning.

FIG. 4 is a schematic view of a prior art inserter.

FIG. 5 is a schematic view of the inserter of the invention in operation.

FIG. 6A is a side, cross sectional view of an alternate embodiment of the inserter of the invention having a drive train locking device.

FIG. 6B is a detail view of the portion 6B of the drive train locking device shown in FIG. 6A.

FIGS. 6C-6D are partial side views of the inserter of FIG. 6A showing the removal of the driver train from within the housing of the inserter.

FIG. 7 is a side view of an alternate embodiment of the drive train locking device of the invention.

FIG. 8 is a side, cross sectional view of an alternate embodiment of the inserter of the invention.

FIG. 9 is a side, cross-sectional view of an inserter head of the prior art.

FIG. 10 is a side, cross-sectional view of the inserter head of the invention.

FIG. 11A is a side view of an alternate embodiment of the invention.

FIG. 11B is a perspective view of the alternate embodiment of the invention.

FIG. 11C is a close up view of a portion B of the embodiment shown in FIG. 11B.

FIG. 12A is a sectional view taken along line A-A of FIG. 11A showing the mechanism in a locked position.

FIG. 12B is the sectional view of FIG. 12A wherein the mechanism is shown in an unlocked position.

FIG. 13 is a top view of a kit of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT(S)

Referring now to FIGS. 1A-1C, an acetabular inserter 10 is provided to aid the surgeon in controlling the installation of an acetabular cup prosthesis 11 having a central, female aperture 13. The inserter 10 has a housing 12 which encloses a drive train 14 having, at a far end, a prosthesis engaging interface 16 (preferably threaded), and at the opposite end, a handle 20 which facilitates turning of the drive train by the operator. The housing 12 may be C-shaped, as shown, in order to minimize the invasiveness of the surgery by better clearing anatomical structures and tissue.

The interface 16 is cut on a boss 22 on a cylindrical piston 24 which slides in an axial hole 26 in the housing 12. The interface 16 is preferably threaded. The piston 24 is connected by way of a first U-joint 30 to a lever 32 which slides in a pivoting sleeve 34 fixed to the housing 12 via a pivot 36. The lever 32 is connected via a second U-joint 40 to a second pivoting lever 42 which is fixed to pivot in a catch 44 on a pivot pin 46. The catch 44 is essentially a divot or a seat cut into the housing 12, against which the pivot pin 46 of the lever 42 is captured when a slide 50 is slide over the pin when engaged against the seat.

A slideable sleeve 52 slides over the lever 42 and has a trunion 54 to which a rod 56 is pivotally attached. The rod 56 passes through a one-way catch 60 in the housing 12. The one-way catch 60 can be a captured split wedge sleeve 62 having an inner diameter that just matches the outer diameter of the rod 56 and which is captured in a recess having a matching conical surface that surrounds the sleeve so as to allow the rod 56 to slide into the housing 12, but to prevent the rod from sliding out of the housing unless an unlock lever (not shown) is activated, such lever merely lifting the sleeve 62 out of engagement with the conical surface so as not to lock and to permit the rod to back out of the housing. Any number of alternative one way lock devices may be used however, the selection of which being within the skill of a person of ordinary skill in this field.

Referring now to FIG. IC, an alternative embodiment of the one way catch mechanism 60 is shown. In this embodiment, the rod 56 passes through a one-way catch 60 in the housing 12. The one-way catch 60 has an inner recess that matches the outer diameter of the rod 56. The inner recess has a ratchet pawl (not shown) that locks against one way ratchet teeth 67 so as to allow the rod 56 to slide into the housing 12, but to prevent the rod from sliding out of the housing unless an unlock lever 68 is activated, such lever merely pulling the pawl away from the teeth to permit the rod to back out of the housing.

A polymeric impactor head 64 is molded over the end of the housing 12, to absorb the impact stresses incurred during use as an impactor. The head 64 is selected so as to have good frictional characteristics as well. Nevertheless, a metal, non-molded head may also be used with satisfactory results.

Referring now to FIGS. 2A-2B, in operation, the interface 16 (preferably threaded) of the piston 24 is engaged with the hole 13 of the prosthesis 11. The operator may rotate the handle 20 about its axis to turn the drive train 14 in order to interface the piston 24 into the hole 13 or to orient the prosthesis in what he believes to be a correct or an initial position. Then, an end 42′ of the lever 42 is urged downwardly toward the housing 12. Such downward movement acts through the drive train 14 to draw the piston 24 into the housing 12, and thus to cause the inner surface of the prosthesis 11 to be drawn against the head 64 so as to create a normal force between the inside of the prosthesis and the head so as to prevent rotation of the prosthesis 11 relative to the housing 12. The operator may use the one way locking mechanism 62 to lock the lever 42 in a position so as to lock the prosthesis 11 against the head 64, thus enabling the surgeon to pre-set and lock the position of the prosthesis prior to the installation thereof. Note that orientation of the prosthesis 11 is important because the prosthesis often has pre-drilled holes 4 (shown in FIG. 4A) and thus, these must be properly positioned prior to fastening through these holes.

The “easily cleaned” objective of the invention enables access to all surfaces that they can be cleaned (parts covering another part can be moved or removed to expose all surfaces), the reduction in number of small radius internal corners, crevices and small gaps and the absence of blind holes.

Referring now to FIGS. 3A-3D, in the embodiment shown, the device 10 is disassembled for cleaning by simply sliding the slide 50 back so as to release the pivot 46 and then lift the drive train 14 out of the housing but allow it to remain pivotally connected at pivot 36. As the drive train 14 is pivoted, the piston 16 is drawn out of the hole 26 in the housing 12. To reassemble after cleaning, the piston 16 is reinserted into the hole 26 and the drive train 14 is rotated back into position, with the one way locking mechanism entering its receiver and the pivot 46 again entering into the catch 44. The slide 50 is then slide over the pivot 46 and the inserter 10 is again ready for use.

Referring to FIGS. 4-5, the inserter 115 and a prior art inserter 15, respectively, are shown passing through a miniature incision 35 in the patient's skin 30. In FIG. 4, the inserter 15 is shown approaching the acetabulum 40 in an orientation desirable to ream the socket 45. The difficulty with the prior art spindle 15 is shown as the shaft 3 impinges on the miniature incision 35 at edge of the incision 37. The current surgical protocols are being pushed to the limits and the incision sizes are being reduced in the hopes of increasing the patient's speed to recovery. In some cases surgeons are using a two-incision approach, one to reach the acetabulum and the other to reach the femur. Either one incision or two incision techniques demand less trauma to the patient requiring the instruments to be more optimally designed to make up for the lack of operating space. The reamer of FIG. 5 shows a new inserter 115, which has a bent housing 113 containing the drive shaft 107.

It is important to place the bends in the housing at critical locations to pass through the miniature incision without impinging on the skin 30 at 37 while still maintaining the same surgical protocol. The reason why the drive end 104 and the holding mechanism 120 need to be in line or on parallel axis is so that the applied force 130 results in an axial motion 140. This allows the surgeon to maintain the existing technique since inherently inserter 15 in FIG. 4 would give the same result since it has a straight drive shaft 3. This allows the surgeon to apply a load directly along the path of reaming.

It should be noted that a second head (not shown) can be mounted onto the front of the device 10, the head formed so as to conform with a surface of an acetabular cup liner, in order to enable the device to seat a liner as well as the cup.

The attached drawings represent, by way of example, different embodiments of the subject of the invention.

Referring now to FIG. 6A and 6B, an alternate embodiment of the inserter 10′ is shown having a safety release 50′ having a pin 50′a connected to a base plate 50′b, and spaced apart and parallel with the pin, a second spring pin 50° C. having a boss 50′d which retains a spring 51, acting between the boss and a surface 12 a of the housing 12. Such an arrangement biases the pin 50′a upward in a position which holds the cross pin 46 of the drive train 14 into place. When the prosthetic cup 11 is not fully seated and the surgeon impacts it by mistake, pins that hold the mechanism together are highly stressed. Therefore, a means to enable the mechanism to break free without damage provides a significant advantage. The pin 50′a has a rounded head so as to facilitate removal of the cross pins 46 from their respective divots 44′ without damage thereto and thus allowing disassembly of the inserter 10′. Further, the retention force of the safety release 50′ is selected so as to release the cross pins 46 from the divots 44′ when the torsion or the stresses on the drive train 14 (for example, from use of the inserter as an impactor) reach a threshold amount. Such stresses typically occur when there is no tension on the drive train 14 and the cross pins 46′ collide with the safety pin 50′a. Using this embodiment, it is also possible to release the cross pin 46′ from the divot 44′ by the operator pulling down on a portion of the plate 50′b that extends beyond the side wall of the housing 12.

Referring now to FIGS. 6C and 6D, release of the cross pins 46 from the divots 44′ is shown.

Referring now to FIG. 7, a second alternate embodiment of the inserter 10″ substitutes the safety release 50′ with an integrated safety release 50″ made up of a flexible finger 50″b extending from the housing (and integral therewith), over the cross pin 46, and retaining the cross pin by means of a blocking head 50″c. The flexible finger is preferably cut using a wire-cut EDM device but may also be formed in a large variety of ways, including by attachment of a separate spring finger (i.e., is not integral with the housing).

It should be noted that a second head (not shown) can be mounted onto the front of the device 10, the head formed so as to conform with a surface of an acetabular cup liner, in order to enable the device to seat a liner as well as the cup.

Referring now to FIG. 8, in another embodiment, an acetabular inserter 10′ is provided to aid the surgeon in controlling the installation of a hip prosthesis 11. The inserter 10′ has a housing 12′ which encloses a drive train 14′ having, at a far end, a prosthesis engaging expandable collet device 120 and at the opposite end, a knob or handle 20′ which facilitates turning of the drive train by the operator. The housing 12′ may be C-shaped, as shown, in order to minimize the invasiveness of the surgery by better clearing anatomical structures and tissue.

When the drive train 14′ is drawn inwardly by squeezing the lever 42 towards the housing 12′, the prosthesis-engaging expandable collet device 120 locks the prosthesis 11 against rotational movement. This enables the surgeon to pre-set and lock the position of the prosthesis 11 prior to the installation thereof. Such selective locking of the prosthesis 11 is important because the prosthesis 11 often has pre-drilled holes 4 and thus, these must be properly positioned prior to fastening through these holes. Further, the expanding of the expandable collet device 120 eliminates the need of threading the acetabular prosthesis 11 onto the end of the inserter 10′ as the prosthesis can simply be placed over the expandable collet 126′ and the expandable collet expanded so as to grip internal threads 122 of the prosthesis 11. Note that to improve likelihood of alignment, the lip 128 on the fingers 127 may be replaced with longitudinally aligned dimples (not shown) having a profile that resembles threads but yet which minimizes the need for precise orientation of the internal threads of the prosthesis and the dimples on the fingers 127 of the expandable collet device 120.

In operation, the prosthesis first is placed over or threaded onto the expandable collet device 120 via a threaded or undercut hole 122. In a second step, the prosthesis 11 is oriented with respect to the form of the inserter 10′, in order to minimally impact soft tissue. In a third step, the handle 160 of the inserter 10′ is gripped and the prosthesis 11 placed through the incision 35. In a fourth step, the inserter 10′ is used to impact the prosthesis 11 in place by impacting a rear portion of the inserter with a mallet, for example. Optionally, with the current design, it is envisioned that the prosthesis 11 be inserted into the incision 35 as a first step, potentially taking advantage of being able to more freely maneuver it into the incision and roughly position it prior to inserting the expandable collet device 120 of the inserter 10′ into a mating hole-this optional procedure is used, the lever 46 may then be pressed towards the housing 12, thereby drawing the plunger 146 a′ in between the fingers 127 thereby actuating the opening of the expandable collet device 120 and thus the fixing the prosthesis 11 on the end of the inserter 10′. These optional steps substitute for the above mentioned four steps. In a fifth step, the knob 20′ is turned in an opposite direction in order to release the prosthesis 11. In a final step, the inserter 10′ is removed from the incision 35. The “easily cleaned” objective of the invention 10, 10′, 10″ enables access to all surfaces that they can be cleaned (parts covering another part can be moved or removed to expose all surfaces), the reduction in number of small radius internal corners, crevices and small gaps and the absence of blind holes.

Referring now to FIG. 9, a cross section of FIG. 12 of a prior art patent application publication No. 20050038443 (the '443 publication), expandable jaws 925 of the prior art are shown. The following is a description essentially copied from the '443 publication:

-   -   Jaws 925 extend out through the face 1200 of cup attachment 920         and are held in place by a retaining ring 1202, a washer 1205,         and a spring 1215 (spring 1215 is a Belleville washer in one         embodiment). An O-ring 1220 urges jaws 925 against actuator 1000         (FIG. 10 of the '443 publication) so that jaws 925 close as         actuator 1000 is withdrawn. Spring 1215 forces jaws 925 out         through face 1200 of cup attachment 920. A gap 1210 between jaws         925 and washer 1205 prevents jaws 925 from taking the force of         hammer blows by allowing jaws 925 to recede into cup attachment         920 until face 1200 engages the interior surface of cup 200.         Face 1200, and not the more fragile jaws 925 and associated         drive mechanism, thus absorbs the impact. A second 0 ring 1220         prevents blood and debris from entering cup attachment 920         between attachment 920 and conduit 905. Though not shown here,         attachment 920 includes female threads on an inside surface 1250         that mate with threads 1100 on the outside of conduit 905 (FIG.         11 of the '443 publication). Further, in the prior art device         shown, the equivalent of the plunger 146 moves outwardly, into a         position between the opposing jaws 925 a and 925 b, to urge the         jaws against opposing surfaces of the implant 11. As with the         embodiment already described, this prior art version grips         essentially at two opposing points on the internal threaded         surface of the implant 11. Further, unlike the embodiment just         described, the action of the plunger does not concurrently help         secure the implant 11 against rotation because it does not         concurrently draw the implant against the face 1200 of the head         of the prior art device.

Referring now to FIG. 10, an improved embodiment 10″ substitutes a single collet 126′ for jaws 925 of the prior art. The collet 126 includes a set of fingers 127 having a bulbous, annular lip 128 which extends around the circumference of the collet 126′. The collet 126 is fixed in position against rotational movement via a tab engaging a keyway and held in place by a Bellville spring 145 interposed between the collet and a threaded collar 142′. The Bellville spring 145 abuts against a flange 126 a to fix the collet in place yet permitting limited axial movement. A plunger 146 a′ moves axially within a central tapered recess 127′ of the collet 126′. The plunger 146 a′ includes a head 146 b′ having an exterior, tapered surface 146e that abuts against an interior surface 127′ of the fingers 127 of the collet 126′. The plunger 146′ is affixed to the drive train 14 so as to be drawn into the housing 12 when the lever 42′ is depressed towards the housing. The initial drawing of the plunger 146 a′ into the housing 12 first causes the tapered surface 146e to press against a corresponding surface 127′ of the collet 126′, and because the fingers resist the plunger less than does the Bellville spring 145, the fingers 127 of the collet first move away from each other, expanding the lip 128 of the collet, so that when a corresponding prosthesis is placed over the lip 128, a corresponding recess 1 la′ of the prosthesis receives the annular lip 128 and thus, is firmly locked in place for insertion in the acetabulum. After the lips 128 of the collet 126 have fully engaged the corresponding recess l a′, further drawing in of the plunger 146a′ causes the collet 126′ to compress the Belleville spring 145 and thus draw the prosthesis 11′ against the impaction face 141 a and frictionally prevents relative rotation thereof. This enables the surgeon to accurately and securely manipulate the prosthesis into final position.

Referring now to FIG. 11A-11C, 12A and 12B, an alternate embodiment of the locking device of FIG. 1C includes a slideable sleeve 52′ slides over the lever 42 and has a trunion 54′ to which a rod 56′ is pivotally attached. The rod 56 has a rack 67′ and passes through a one-way catch 60′ in the housing 12′. The one-way catch 60′ has an inner recess that matches the outer diameter of the rod 56′. The one-way catch 60′ is a pawl 62′ which pivots on a pin 63 fixed to the housing 12′ such that the pawl pivots on an axis which is substantially perpendicular to the axis of the rod 56′. The catch 60′ is biased by a spring 65 in a spring housing 13 so that teeth 60 a′ of the catch engage the teeth 67′ of the rod 56′ to ensure that the rod locks progressively as the lever 42 is pressed toward the housing 12′. The rod 56′ is held firmly in place, even during heavy impacting, unless an unlock lever 62 b′ is pressed thus permitting the rod to back out of the housing 12. Any number of alternative one way lock devices may be used however, the selection of which being within the skill of a person of ordinary skill in this field.

The inner recess has a ratchet pawl (not shown) that locks against one way ratchet teeth 67 so as to allow the rod 56 to slide into the housing 12, but to prevent the rod from sliding out of the housing unless an unlock lever 68 is activated, such lever merely rotating the teeth 60 a′ of the pawl away from the teeth 67′ of the rod (as shown in FIG. 12B) to permit the rod to back out of the housing. The placement of the pin 63 of the pawl 62′ so that it is perpendicularly located with respect to the axis of the rod 56 is important because in this position, shock during heavy impaction tends to tighten the locking between the teeth 67′ of the rod 56′ and the teeth 60 a′ of the pawl 62′ (see in particular, FIG. 12A).

Referring now to FIG. 13, a kit 200 includes the impactor 10, a variety of prosthetic implants 11, 11′, and 11″, as well as a case 18 which conveniently holds the components of the kit in place so as to be readily available when needed.

In an advantage, the multiple fingers 127 of the collet 126′ of FIG. 11 more evenly distribute the forces to the prosthesis 11, thus avoiding damage to the surfaces thereof which the fingers contact. Further, such multi-point contact allows for more firm fixing of the prosthesis 11 for more accurate and precise placing of the prosthesis in the acetabulum, as compared to jawed type devices of the prior art.

In another advantage, the locking action in which the plunger 146 a′ is drawn into the housing 12, concurrently pulls the prosthesis 11 into engagement against the face 141a of the inserter head 141, thus further securing the prosthesis 11 and providing significantly better handling thereof.

In an advantage, the inserter 10′ is simple and easy to use, without complex and possibly confusing locks activated with the thumb.

In another advantage, it is simple to select a desired orientation of the prosthesis 11.

In another advantage, due to the drawing of the prosthesis 2 against the impaction head 40, the connection between the prosthesis 11 is robust as the connection is made without any play or gaps therebetween, ensuring good support during impaction.

An objective is to provide an inserter 10, 10′, 10″ that is easy to disassemble and for which the disassembly is easy to learn.

Another object of the invention is to provide a dual mechanism that uses common components to lock the implant in place as well as to provide for easy disassembly for cleaning and sterilization.

Another object of the invention is to minimise the number of pieces and the risk that parts could be lost.

The object of the invention is to provide an inserter 10, 10′, 10″ which enables the implant to be locked in an angular orientation prior to installation of the implant.

In an advantage, the inserter 10′ is simple and easy to use, without complex and possibly confusing locks activated with the thumb.

In another advantage, it is simple to select a desired orientation of the prosthesis 11.

In another advantage, due to the drawing of the prosthesis 2 against the impaction head 40, the connection between the prosthesis 11 is robust as the connection is made without any play or gaps therebetween, ensuring good support during impaction.

An objective is to provide an inserter 10, 10′, 10″ that is easy to disassemble and for which the disassembly is easy to learn.

Another object of the invention is to provide a dual mechanism that uses common components to lock the implant in place as well as to provide for easy disassembly for cleaning and sterilization.

Another object of the invention is to minimize the number of pieces and the risk that parts could be lost.

The object of the invention is to provide an inserter 10, 10′, 10″ which enables the implant to be locked in an angular orientation prior to installation of the implant.

The attached drawings represent, by way of example, different embodiments of the subject of the invention. Multiple variations and modifications are possible in the embodiments of the invention described here. Although certain illustrative embodiments of the invention have been shown and described here, a wide range of modifications, changes, and substitutions is contemplated in the foregoing disclosure. In some instances, some features of the present invention may be employed without a corresponding use of the other features. Accordingly, it is appropriate that the foregoing description be construed broadly and understood as being given by way of illustration and example only, the spirit and scope of the invention being limited only by the appended claims. 

1. An acetabular impactor for aiding a surgeon in controlling the installation of a hip prosthesis, the impactor comprising: (a) an impactor head; and (b) a housing attached to the impactor head, the housing enclosing a drive train having, at a far end, a prosthesis engaging element, and at the opposite end, a handle which facilitates turning of the drive train by the operator; wherein the opposite end of the drive train has a latch device which enables opening of the impactor for cleaning and sterilization.
 2. The acetabular impactor of claim 1, wherein the drive train includes at least one u-joint located so as to transmit torque through a bend in the housing.
 3. The acetabular impactor of claim 1, wherein the housing is C-shaped.
 4. The acetabular impactor of claim 1, wherein the locking mechanism comprises a drive train having a prosthesis engaging tip, the drive train further including a lever link which is disposed in the housing so as to rotate on a fulcrum, such that, actuation of the lever link draws the tip into the housing which in turn expands a collet having a projection and, when connected to a prosthesis, expands the projection of the collet into a corresponding feature of the prosthesis, thereby engaging the prosthesis, wherein further drawing in of the tip draws the prosthesis against an impaction surface, thus permitting the generation of sufficient friction therebetween to firmly lock the prosthesis in place.
 5. The acetabular impactor of claim 4, wherein the link lever has a knob attached to a distal end, the knob enabling a user to orient the tip.
 6. The acetabular impactor of claim 1, wherein a lockable, variable length link is attached between the link lever and the housing in order to permit a user to lock the link lever at positions so as to permit a user to vary pressure that a prosthesis is held against the impaction head.
 7. The acetabular impactor of claim 6, wherein the variable link is infinitely variable and unlockable via a latch in order to permit release of pressure on the prosthesis.
 8. The acetabular impactor of claim 7, wherein the prosthesis engaging tip is connected by way of a first U-joint to a lever which slides in a pivoting sleeve fixed to the housing via a first pivot.
 9. The acetabular impactor of claim 1, wherein a one-way catch mechanism prevents a rod connected to the second lever from sliding out of the housing unless an unlock lever is activated.
 10. The acetabular impactor of claim 1, wherein the impactor head is covered by an impactor head covering, made of a shock-absorbing material, in order to absorb the impact stresses incurred during use of the impactor.
 11. An acetabular impactor of claim 1, wherein the locking mechanism is an expandable collet mechanism which a plunger expands when drawn into the collet so as to lock the expandable collet against a surface of a prosthesis in order to prevent the prosthesis from rotating, thus enabling the surgeon to pre-set and lock the position of the prosthesis prior to the installation thereof.
 12. The impactor of claim 11, wherein the collet mechanism is comprised of at least three fingers each having a distal, prosthesis-engaging end which is adapted to engage an interior surface of a prosthesis, the prosthesis-engaging ends being drawn away from one another when an actuator piston is draw therebetween, thereby eliminating the need of threading the acetabular prosthesis onto the tip of the impactor as the prosthesis can simply be placed over the expandable collet and the expandable collet expanded so as to grip at least one internal recess of the prosthesis.
 13. The impactor of claim 12, wherein the fingers of the collet mechanism are provided with external, three-dimensional structures which engage with corresponding structures on the prosthesis.
 14. The impactor of claim 13, wherein the three dimensional structures are threads.
 15. The impactor of claim 13, wherein the three-dimensional structures are grooves.
 16. The impactor of claim 13, wherein the three-dimensional structures are divots.
 17. The acetabular impactor of claim 11, wherein the drive train includes at least one u-joint located so as to transmit torque through a bend in the housing.
 18. The acetabular impactor of claim 11, wherein the housing is C-shaped.
 19. An acetabular impactor for aiding a surgeon in controlling the installation of an orthopaedic prosthesis, the impactor comprising: (a) an impactor head; (b) a housing attached to the impactor head, the housing enclosing a mechanism having, at a far end, a prosthesis engaging element, and at the opposite end, a handle which facilitates turning of the drive train by the operator; and (c) a latch device which latches the mechanism in functional orientation to the housing, and which is readily releasable to enable at least partial removal from the housing for cleaning and sterilization.
 20. A surgical kit for minimally invasive surgery, the kit including: (a) a case having recesses into which components of the kit may be conveniently stored until use; (b) at least one orthopaedic implant; and (c) an impactor for aiding a surgeon in controlling the installation of the orthopaedic implant, the impactor comprising: (i) an impactor head; (ii) a housing attached to the impactor head, the housing enclosing a mechanism having, at a far end, a prosthesis engaging element, and at the opposite end, a handle which facilitates turning of the drive train by the operator; and (iii) a latch device which latches the mechanism in functional orientation to the housing, and which is readily releasable to enable at least partial removal from the housing for cleaning and sterilization10, a variety of prosthetic implants 11, 11′, and 11″, as well as a case 18 which conveniently holds the components of the kit in place so as to be readily available when needed.
 21. An acetabular impactor for aiding a surgeon in controlling the installation of an orthopaedic prosthesis, the impactor comprising: (a) an impactor head having a prosthesis engaging element comprising at least three fingers, the fingers each having a lip formed to engage an interior recess of a prosthetic implant, wherein the prosthesis engaging element is a collet which is fixed against rotational movement relative to a drive train; (b) a drive train fixed to operate within a housing, the housing being attached to the impactor head, the drive train having, at a far end, the prosthesis engaging element, and at an opposite end, a handle which facilitates turning of the drive train by the operator; and (c) a latch device which latches the mechanism in functional orientation to the housing, and which is readily releasable to enable at least partial removal from the housing for cleaning and sterilization, wherein the collet is fixed in position against rotational movement via a tab engaging a keyway and held in place by a Bellville spring interposed between the collet and a threaded collar, the Bellville spring abutting against a flange of the collet to fix the collet in place yet permitting limited axial movement thereof, wherein further a plunger, attached to the drive train, moves axially within a central tapered recess of the collet and includes a head having an exterior, tapered surface that abuts against an interior surface of the fingers of the collet, the plunger further being affixed to the drive train so as to be drawn into the housing when the lever is depressed towards the housing. 